Cleaning land for wealth (CL4W) is an EPSRC-funded and CL:IRE-supported project that aims at developing a combined process of land phyto-remediation, lignocellulosic degradation and production of industrially-useful chemicals and catalysts. The CL4W is a collaborative project led by the University of Warwick with Edinburgh, Cranfield, Birmingham and Newcastle Universities.
Arsenic is known to be the most toxic metal pollutant in the world. Although the UK's industries ceased to use arsenic more than a decade ago, thousands of hectares of land remain contaminated and abandoned, especially in Cornwall, where arsenic was intensively mined and processed in the last century.
The desert-like view of Devon Great Consols mine (left) with 17 g of arsenic per kg soil and a tank of arsenic that leaks into nearby stream at Redmoor mine (right) in Cornwall.
Contamination of land with platinum group metals has become scrutinized within the last two decades. Car converters, which were introduced to reduce exhaust fumes, appeared to erode and pollute roadside soil and watercourses with platinum and palladium. We estimate that about 2 tonnes of platinum is currently deposited along the UK’s roads and the emission rate reaches as high as 12 kg per year.
Phyto-remediation, which is a method of cleaning land by using hyper-accumulating plants, is a low-cost and environmentally friendly technology. Combined with rapidly developing biomass degradation processes, phyto-extraction has become an economically attractive method for remediating brownfield sites.
Ferns are known to be arsenic hyper-accumulators with Pteris Vittata, commonly known as Chinese brake fern, being the most effective. We will be also studying native to the UK types of ferns, like the depicted Dryopteris.
Up until recently there was no better way to recover metals than incineration of plants and subsequent extraction of the metals with strong acids. Our proposal is to degrade biomass with the help of fungi and bacteria in order to “unlock” the metals in accumulating plants and at the same time to produce phenol-based chemical building blocks for the pharmaceutical industry and other useful products, like vanillin and ferulic acid.
The metals, released into a water-based mixture, will be reduced with the help of “bio-factories”, Desulfovibrio desulfuricans, yielding bio-functionalised nanoparticles which after isolation and modification can be used to treat cancer (arsenic) or as catalysts (platinum and palladium).
Desulfovibrio bacteria with extracellular Pt nano-particles.
While cleaning land from metallic contaminants as arsenic, platinum and palladium we will produce catalytically active nano-particles from recovered metals and useful chemicals from lignocellulose.